Absorption refrigeration apparatus including means cooling strong absorption solution

ABSTRACT

ABSORPTION REFRIGERATION APPARATUS EMPLOYING A PUMP FOR CIRCULATING ABSORBENT SOLUTION WHICH IS AT A TEMPERATURE AND PRESSURE NEAR ITS FLASH POINT IN WHICH A HEAT EXCHANGER IS PROVIDED TO REDUCE THE TEMPERATURE OF THE SOLUTION PRIOR TO ITS FLOW TO THE PUMP THUS PREVENTING FLASHING OF THE SOLUTION AS THE PRESSURE IS REDUCED AT THE INLET OF THE PUMP.

Jan. 12, 1971 L M,HQ| MAN Y 3,553,977 fABsoRPTION REFRIGERATION APPARATUS INGLUDINGMEANS COOLING y. STRONG ABSORPTION SOLUTION.

' Filed Nov. 5, .1968

4e lFIG. l"

' INVEN'roR. FIG. 2 JOHN L M. HoLMAN nBY 0 ATTORNEY United States Patent O ABSTRACT oF THE DlscLosURE Absorption refrigeration apparatus employing a pump for circulating absorbent solution which is at` a temperatureV and pressure near its ash point in .which a heat exchanger is provided to reduce the temperature of the solution prior to its flow to the pump thus preventing flashing'of the solution as the pressure is reduced at' the inlet of the pump.

It has been found that'in the operation of an absorption refrigeration machine employing pumpsfor circulating the absorbent solution that the pressure and temperature of the solution flowing to the pump is so close ice evaporator might be in a second shell with conduits therebetween for conducting fluids.

Various combinations of refrigerant and absorbent may be used. A solution of lithium bromide and Water has been found to be highly satisfactory for use.

The absorber 18 has a coil 20` supplied 'withv cooling fluid from a source 22 to remove heat from the absorber. This cooling fluid is conducted by a conduit 24 to a cooling coil 26 in the condenser 12 and the cooling uid leaves the machine through a conduit 28. The cooling coil 26 in the condenser 12 removes heat from and condenses the refrigerant vapor in the condenser.

The generator 14 has a heating coil 30 supplied ywith heating fluid from a source S2. The heating fluid is discharged from the coil 30 through a conduit 34. The coil =30 heats the absorbent solution in the generator causing it to boil and force refrigerant vapor into the condenser 12. The condensed refrigerant in the condenser 12 flows through an opening 36 into the evaporator 16. The absorbent solution in the absorber 18 reduces the pressure in the absorber 18 and in the evaporator 16 Y` by the absorption of refrigerant vapor, 'thus causing the to its ash point that the reduction of pressure atthe inlet of the pump is sufficient to cause ashingor socalled cavitation in the pump. 'Y

Cavitation in the pump is undesirable because the output and eiciency of the pump are reduced. Also the cavitation can cause erosion in the impeller of the pump. Furthermore the cavitation causes an objectionable noise.

Various constructions have been employed to avoid flashing of the absorbent solution. One such scheme involves the flashing in a chamber which is in communication with the low pressure in the absorber. This requires the use of a comparativelyflarge and expensive chamber and the flashed gas is a load on the absorber.

Another construction which has been employed involves introducing thev concentrated solution to the absorber space Where it flashes before passing to the pump. Again the ash gas is a load on the absorber. Also additional piping is required;

It is an object of this invention to provide a heat exchanger which `will transfer heat from the solution to a heat sink thus reducing the temperature ofthe solution to such an extent that it will not flash in the inlet of the pump where the pressure is reduced.

It is afurther object of this invention to provide control of the rate of ow of cooling fluid through the heat exchanger to prevent overcooling and solidication of the solution.

Other objects and advantages of the invention will become apparent as the specification proceeds to describe the invention with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic view of a rst form of the invention in which the -concentrated solution is cooled before admixture with dilute solution.

FIG. 2 is a diagrammatic view of a second form of the invention in which the concentrated solution is mixed with dilute solution, before passage through the heat exchanger. Referring now to FIG. l, the absorption system shown is of the type having a single shell 10 with a partition 11 separating a high pressure chamber containing a condenser 12, and a generator 14 from a low pressure chamber containing an evaporator 16V and an absorber y18. It should be understood that other arrangements might tbe used; for instance, the generator and the condenser might be in one shell and the absorber and refrigerant in the evaporator 16 to boil. A low temperature is thus maintained in the evaporator 16.

Evaporator 16 has a coil 38, Fluid from a refrigerating load such as an air conditioningsystem enters the coil 38 through a conduit 40. This uid is reduced in temperature in the coil 38 andreturns to the refrigerating load through conduit 42. The liquid refrigerant in the evaporator 16 flows through a conduit 44 to a pump 46 which is driven by a motor not shown. Pump 46 has a discharge conduit 48 for conducting the fluid discharged by the pump to a spray tree 50 in the evaporator 416.

Concentrated absorption solution flows from generator 14 through a conduit 52 to heat exchanger 54 and thence through a conduit 56 to heat exchanger 58]. The concentrated solution flows from heat exchanger 58 successively through conduits 60 and 62 to -pump 64. Dilute solution flows from absorber 18 successively through conduits 66 and 62 to pump 64. The mixed concentrated and dilute solution fiows from pump 64 through conduit 66 to spray tree 68 in the absorber 18.

Dilute `solution flows from absorber 18 through conduit 70 to pump 72 which discharges the dilute solution through conduit 74 from which it ows through heat exchanger 54 and thence thlrough conduit 76 to the generator 14 to be concentrated.

The heat exchanger 58 is supplied with cooling heat exchange iluid from a source 78 which may be a cooling tower, a well, a pond, or any other suitable- -heat sink. A valve 80 regulates the ow of water from the source to the heat exchanger 58. The water returns from the heat exchanger 58 to source 78 or to waste through conduit 82.

The valve 80 has a bulb 84 in sensing relationship to the solution leaving the heat exchanger 58 and prevents the leaving solution temperature from exceeding a predetermined value. For instance, in an absorption machine without the heat exchanger 58, the solution might be at a temperature of 130 F. The valve 80 could start to open at 110 F. and be fully open at 115 F. thus eliminating the possibility of cavitation at the entrance to the pump 64.

Reference is now to FIG. 2 of the drawings in which like parts contain the numerals of the corresponding parts in FIG. 1.

In the form of iFIG. 2 the absorbent which has been cooled in heat exchanger 54 flows through conduit 86 and mixes with dilute solution flowing in conduit 88. The mixed absorbent then passes through heat exchanger to the inlet of pump 92. -From pump 92, the absorbent flows through conduit 94 andgis discharged in the absorber from a spray tree 96. The heat exchanger 90 is supplied with cooling uid in a manner similar to that described with reference to FIG. 1. A valve 97 controls the ow of cooling uid responsive to the temperature of solution leaving the heat exchanger 90 as sensed by bulb 98.

In the form of the invention of FIG. 2 the solution entering the heat exchanger 90 is more dilute than the solution entering the heat exchanger 58 in FIG. 1 and therefore it may be cooled to a lower temperature without risking solidication.

For instance, the solution owing through conduit 86 might be about 130 F. and the temperature of the dilute solution in conduit 88 might be 105 'F. The valve 97 could be set to start to open when the temperature leaving the heat exchanger 90 exceeds 90 F. and be fully open when the temperature of the mixture leaving the heat exchanger 90 reaches 95 F.

Having thus described in detail the preferred embodiment of my invention, I contemplate that many changes may be made without departing from the scope or spirit of my invention and I accordingly desire to be limited only by the following claims.

I claim:

1. Absorption refrigeration apparatus comprising an absorber, an evaporator, a condenser and a generator placed in a closed circuit, the circuit containing a solution of an absorbent and a refrigerant, first conduit means for conducting absorbent from said absorber to said generator, second conduit means for conducting absorbent from said generator to said absorber, rst heat exchange means for exchanging heat between said rst conduit and said second conduit, a pump in said second conduit downstream of said rst heat exchange means, second heat exchange means between said rst heat exchange means and said pump, and circuit means in said second heat exchange means for conducting a cooling iluid from a heat sink which is external to said refrigeration apparatus.

2. Absorption refrigeration apparatus according to claim 1 and having means for conducting absorbent from said absorber to said pump.

3. Absorption refrigeration apparatus according to claim 1 and having means for conducting absorbent solution from said absorber to said pump downstream of said second heat exchanger.

4. Absorption refrigeration apparatus according to claim 1 and having means for conducting absorbent solution from said absorber through said second heat exchanger to said pump.

S. Absorption refrigeration apparatus according to claim 1 and having a valve in said circuit means for said second heat exchanger which is responsive to the temperature of solution leaving said second heat exchanger to increase the flow of cooling uid as the temperature of solution downstream of said second heat exchanger tends to exceed a predetermined value.

References Cited UNITED STATES PATENTS 3/ 1964 Stubbleeld 62-335 1/1967 Aronson et al. 62-476 

